An optical fiber consists of a core surrounded by a cladding layer. Both the core and the cladding layer are made of dielectric materials. Glass fibers belong to the most popular type of optical fibers whose core and cladding layer are both made from silica. Furthermore, a protection buffer layer is coated outside the cladding layer to protect the very delicate strands of silica fiber from moisture and physical damage. An optical fiber buffer could include one or two protection layers that are applied during the fiber draw.
There exist many different coating options for different applications and each has its particular strengths. The most common coating materials for glass fibers include acrylate, high-temperature acrylate, fluoroacrylate, silicone, silicone/acrylate, polyimide, carbon, metal, and the like. Some fibers even have two layers of coatings, with a softer inner layer and a much stiffer outer layer to respectively cushion the glass from external mechanical loads and also protect the fiber from abrasion.
Optical fiber coating stripping is an essential fiber preparation step, involved in almost all fiber optic component fabrications, fiber processing, or fiber terminations. Based on different purposes, a fiber stripping could be at the fiber tip end (i.e., end-stripping) or in a middle zone of the fiber (i.e., window-stripping). For examples, end-stripping is needed for fiber termination before a fiber connecrization or a fiber splicing, while window-stripping is needed before making a fused coupler or before writing a fiber Bragg grating.
Traditional fiber coating stripping technologies may be mechanical (or thermal-mechanical) based and chemical based. Mechanical or thermal-mechanical stripping may involve physical interference between the stripper blade and the fiber glass surface, which may introduce cracks on the fiber glass and thus degrade the fiber tensile strength. Chemical stripping uses hot acid or solvent, which may introduce possibility of chemical solutions entering into the space between the cladding and coating. Thus, with chemical stripping, serious consequences in time, causing damage of the core may result. Besides, chemical stripping involves obvious safety and environmental issues.
Plasma stripping and laser stripping are newer fiber stripping techniques developed in recent years. They both belong to a “non-contact” stripping process (although the fiber is still contacted by hot air steam or laser light beam). For example, there exist several plasma-based solutions that use either a traditional two-electrode configuration or a multi-electrode configuration. In these solutions the electrodes are disposed in a specific gas or a vacuum (or partial vacuum) ambience.
Several commercial “non-contact” stripping apparatuses have been released in the past years, including plasma-based strippers and laser-based strippers. However, they are all limited to stripping polyimide coating only.
Thus, there is a need for a “non-contact” stripper. First of all, there is a need for a solution that is able to strip most common types of fiber coatings. Furthermore, there is a need for a solution that can work under an ambient condition and require low maintenance.